Downhole tools such as, for example, wirleline, coiled tubing, and drill string deployed tools, are commonly used in a wellbore to sample fluid from a subterranean formation through which the wellbore passes. Such downhole tools may alternatively or additionally be used to measure one or more parameters or properties associated with a wellbore and/or formation such as, for example, temperature(s), pressure(s), rock properties, etc. at various depths.
The depth at which a downhole tool is located within a wellbore may be crucial. For example, when sampling a formation, it may be important to control the depth of the sampling tool so that a sampling probe of the sampling tool is relatively precisely aligned with the formation or a portion of the formation. Various known techniques such flagging, which is used in the case where a downhole tool is deployed via a wireline, and gamma ray correlation techniques, which may be used with drill string, wireline, and coiled tubing deployed tools, can be used to control the depth at which a downhole tool is located within a wellbore. However, in the case where multiple downhole tools are used to accomplish a series of operations within a wellbore and/or in connection with a formation, it can prove difficult to align a second downhole tool at a given location (e.g., a particular depth and/or orientation) within a wellbore to perform a second operation (e.g., a sampling operation) after a first operation (e.g., injection of a fluid into the formation) has been performed by a first downhole tool at that location.